Various apparatus for sealing carton closures are known. In one type of apparatus, tape is applied to the top and/or the bottom panels of the carton to seal the closure flaps in closed condition, there additionally being sufficient tape applied to overlap the front and rear end wall panels, i.e., to extend up and down a distance on such end panels. When using apparatus such as that described in U.S. Pat. No. Re. 26,650, no difficulty is encountered in keeping the carton squared on the conveyor which transports the carton through the apparatus. Such apparatus has clamping guidance side rails as well as a flight conveyor which insures that the end wall panels of the carton are maintained in a disposition transversely perpendicular to the straight line travel course of the carton through the apparatus and thus can engage the transversely disposed wipe down rollers readily uniformly in a contact therewith extending the full length of the rollers. On the other hand, and in instances where no such carton or guidance means are employed in the apparatus and which can insure such squared carton condition during its travel through the apparatus, the carton received on the conveyor can be or becomes displaced from its squared position thereon such as to present a condition in which the end wall panels are skewed relative to the intended fixed travel course. As a consequence, the wipe down rollers which are generally transversely perpendicularly disposed to the travel course will engage only a part of the lateral expanse of the applied tape on such end wall panels and the remainder expanse will not be properly sealed against the carton and wall panels. This is undesirable as it produces improperly sealed cartons. It is also possible for a carton to have its square or rectangular profile distorted while it is in the taping apparatus. Thus, under certain circumstances and where side guidance rails are used, the pressure of the guidance rails can pinch the carton to deform it from a square or rectangular profile to one of a parallelagram in which the front and rear panels are skewed relative to the longitudinal travel course of the carton, even though the side walls of the carton are held parallel to and moved parallel with such travel course. The same problem of ineffective wipe down roller contact is thus encountered.